Summer tells Tom that people used to call her anal girl, it's then clarified that this was because she was a clean freak.
Tom and Summer are in a sexual relationship, but it's never overtly shown. In one instance, you see her bare back, as Tom walks toward her (a subtle homage to 'The Graduate'), and in two or three instances, they're seen kissing on a bed.
Tom and Summer rent a pornographic movie called "Sweet and Shower", and as they watch it (nothing shown or clearly heard), she says "That's doable." You then see a shower curtain, as the water runs, and frantic movement is seen (sex is implied).
Summer tells Tom about one of her ex-boyfriends, whom she called "The Puma". A picture is shown of the man, and the camera zooms in on the man's bulge shown through his pants.
Sexual references are made throughout: a brief scene where Tom and Summer go to an art gallery with art that looks like sexual organs and pieces of excrement; one picture includes two dogs having sex. They go to a movie that is called "Part Vampires, part Giants: Vagiants"; They go to a park (with kids around) and yell out "penis" ( a several times, very loud) louder than the other as a bravery challenge. Brief reference to a hand job and a "humjob".